What you see is what I would want to see with my unit.
With exactly the setup that you describe (2 unlatch passive FS connected to tip 2 and ring 2) I get the following result:
Pressing the "nextprog" FS will let the H8000FW jump from program n to n+1 and then automatically back to n. Alternatively, pressing "nextprog" FS will let the H8000FW jump from program n to n-1 and then automatically back to n. There are more possible scenarios I have seen in the meantime, but overall what definitely will not happen is that the H8000FW jumps from program n to n+1 and stay at n+1.
If I then unassign "prevprog" from ring 2 , then the "nextprog" FS will act as it should.
Above all I can say that my H8000FW behaves not as designed, almost unpredictable, as soon I have assigned more than 1 switch or pedal to tip 1,2 and/or ring 1,2.
With only 1 switch or pedal assigned, the H8000FW behaves perfectly well.
I have 5.3, and the H8000FW is not more than 4 weeks old. .
Since this is the OS version you currently ship I thought that this is aan acceptable and supported OS.
Should I move to 5.5?